To announce or not to announce: What is known about the 2016–2017 influenza season in Hong Kong?

Emerging Microbes & Infections (2017) 6, e78; doi:10.1038/emi.2017.76; published online 6 September 2017

pattern for the 2014-2015 and 2016-2017 seasons, in which people aged 50-64 and ⩾ 65 were most severely affected (Table 1). Underlying diseases and immunosuppression are common in the severe cases in these age groups. The pattern was not seen for the two H1N1 seasons in 2013-2014 and 2015-2016. Furthermore, the rates for influenza-associated hospitalization, severe cases and deaths in the 2016-2017 season in Hong Kong were generally within the boundaries expected for a H3N2 season and comparable to those in other countries and regions in this and previous H3N2 seasons. The disease burden of seasonal influenza is substantial. As estimated by the Centers for Disease Control and Prevention (CDC), there might have been 9.2-35.6 million cases of influenza-related illnesses, 140 000-710 000 hospitalizations and 12 000-56 000 deaths annually in the United States since 2010. For example, in the H3N2-dominant 2003-2004 season, the estimated number of influenza-associated deaths with underlying respiratory and circulatory causes in the United States was 48 614. 3 The advanced influenza surveillance system in Hong Kong has just provided a reallife example in support of the estimation made by the CDC.
The Center for Health Protection of Hong Kong has done a superb job in providing near real-time monitoring of seasonal influenza activity in the territory. Starting from the 2014-2015 season, they went one step further to announce their findings, including the numbers of severe seasonal influenza cases and deaths to the general public. This real-time weekly update of influenza activity helps to increase the awareness and vigilance of people against the risk. However, it has also triggered extensive media coverage, including exaggerated description and unfair comparison, which cause panic, anxiety and overreaction from residents, visitors and people from other regions.
Influenza-associated excess deaths with underlying diseases are difficult to track and might not be detected timely by the influenza surveillance system in adjacent regions. Hence, a comparison of numbers between different regions cannot reflect the severity of seasonal influenza activity. Human infection of avian H5N1 and H7N9 viruses has a case fatality of 60% and 40%, respectively. Likewise, about of 10% of cases with SARS and 30% of cases with Middle East respiratory syndrome are fatal. These are emerging viral pathogens with unusual properties. If seasonal influenza is a known evil, they are unknown beasts. Direct comparison of the numbers of deaths caused by seasonal influenza and these emerging viruses is therefore misleading.
Increasing the transparency of influenza surveillance and sharing more information about seasonal influenza activity with the public should not be discouraged. In other words, not to announce is not an option, but the question is how to explain to all stakeholders and educate them about seasonal influenza, emerging microbes and infections. There is much room for improvement in this aspect.
The numbers of severe influenza cases and deaths in the 2016-2017 season in Hong Kong remind us of the significant morbidity and mortality caused by seasonal influenza. Reducing the disease burden and the impact on public hospitals in Hong Kong is our next challenge. The percentage of people in the high-risk groups, including children, the elderly and health professionals, in Hong Kong who receive influenza vaccination is relatively low. Providing more incentives, including more attractive subsidizing schemes, to these groups might be helpful. Prescribing Tamiflu to the elderly who are at higher risk has also been shown to be a safe and effective prophylactic measure. Earlier concerns about the possibility that exposing more people to Tamiflu might accelerate the development of drug resistance can be relieved. 4 Nevertheless, seasonal influenza will still keep us busy in the years to come. New types of vaccines and antivirals are required in our battle against influenza viruses.